摘要:

A series of field, greenhouse, and laboratory studies were undertaken to elucidate the role of allelopathy in old-field sugar maple stands. Old-field weed residue inhibited germination and growth of maple even in the absence of competing vegetation. Goldenrod and aster were important producers of water soluble compounds that inhibited germination, nutrient uptake, and growth. These allelopathic chemicals were most readily extracted from putrefied plant residues, but they appeared to be natural plant products rather than microbial breakdown products. The deleterious effects of goldenrod on nutrition and growth of maple were overcome by large additions of soluble phosphorus fertilizer.

ISSN:0045-5067    

DOI:10.1139/x78-001

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

White pine (PinusstrobusL.) seedling distributions were sampled around isolated seed trees located on 12 study areas within hardwood stands. Seedling densities were found to differ significantly in different directions from the apparent seed source. Pooled densities from all study areas were lowest and highest in the southwest and northeast quadrants, respectively. With some exceptions, the Weibull probability density function was helpful in describing the general shape of the seedling distributions. Correlations between estimated Weibull parameters and stand characteristics surrounding each seed source suggest that the shape of seedling density distributions is not strongly related to stand characteristics. Implications for modeling seed dispersal are also discussed.

ISSN:0045-5067    

DOI:10.1139/x78-002

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

In six experiments over a 3-year period with 96 12- to 14-year-oldPinuselliottiivar.elliolliiEngelm. ortets, cuttings from shoots girdled and treated with a special rooting powder (containing 1% each indolebutyric acid, 1-phenyl-3-methyl-5-pyrazolone, andn-dimethylaminosuccinamic acid, plus 10% each powdered sucrose and captan) rooted faster, had larger root systems, and survived better both before and after rooting than nongirdled cuttings given the same powder. About 33% of cuttings taken 2 months after a June or July girdle rooted, but only 1% of the nongirdled ones did. Rooting success increased from January girdling to a June–July peak, then decreased to a low in late October.

ISSN:0045-5067    

DOI:10.1139/x78-003

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The roots of 435 dead or dying saplings, averaging 10 years of age, of seven conifer species from the Boreal Forest of northern Ontario were examined for root rot. Only trees with no obvious cause of death or decline, other than root rot, were selected. Eighty-three percent of the trees had root rot. Cultures revealed thatArmillariamellea(Vahl ex Fr.) Kummer was associated with root rot in 68% of all trees examined, including more than 45% of the trees in each species. Ten other root-rotting fungi were isolated from 1% or fewer of the trees, 7 of them from balsam fir (Abiesbalsamea[L.] Mill.) and 3 from black spruce (Piceamariana[Mill.] B.S.P.).Scytinostromagalactinum(Fr.) Donk was isolated from sapwood of roots and lower stems of red pine (PinusresinosaAit.), balsam fir, white pine (P.strobesL.), and black spruce and appeared to be parasitic on these species.Coniophoraputeana(Schum. ex Fr.) Karst. was apparently associated with the death of one balsam fir.

ISSN:0045-5067    

DOI:10.1139/x78-004

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Usefulness of classifying Douglas-fir seed lots using heatsum–emergence relationship parameters was examined by (1) comparing nursery emergence with that predicted by the relationship, (2) testing seed lots for conformity to the relationship, and (3) computer simulation of emergence under various temperature regimes. The emergence parameters used were threshold heatsum (degree-hours above 0 °C that must be accumulated before emergence starts), emergence coefficient (percentage emergence per thousand degree-hours above the threshold), slow emergence percentage (percentage emergence at which the emergence rate is reduced), and slow emergence factor (amount by which the emergence coefficient is reduced). Emergence of seed lots at two nurseries was accurately predicted by a computer model based on the heatsum–emergence relationship. Five seed lots sown in growth chambers under two temperature regimes showed good conformity to the relationship. Computation of emergence percentage and days to 50 or 100% emergence was carried out by a computer model using various emergence parameter values chosen from the observed range and simulated temperature regimes comprising daily heatsums at the 0.5-cm soil depth for 40 days after sowing. These heatsums were derived by regression equation from air temperatures at a forest nursery and were increased or decreased to represent warm or cool regimes or combinations of both. Generally, emergence percentage increased and number of days to 50 or 100% emergence decreased as emergence coefficient and slow emergence percentage increased and threshold heatsum decreased. Emergence percentage was affected by temperature regime only at low emergence coefficients. Number of days to 100% emergence was affected by temperature regime only at average or high emergence coefficients.

ISSN:0045-5067    

DOI:10.1139/x78-005

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Two experiments with red pine (PinusresinosaAit.) were established on 1 + 0 beds at Midhurst Nursery in 1966 and 1967 to study the effects on planting stock of two seedbed densities (160 and 320 trees/m2) and three fertilization levels of topdressing (superficial application of dry fertilizer: control (none), normal, and double). Observations were made as trees were lifted at 3 + 0 and also in the field 5 years after outplanting.Lower seedbed density produced heavier trees, larger stem diameters, and in most cases lower top–root ratios for outplanting. It also resulted in higher survival and taller trees at 5 years after outplanting. The normal 'N' fertilization did not significantly affect tree size in the nursery but was related to decreased survival rate and performance after outplanting.Comparisons with white pine (P.strobasL.) and white spruce (Piceaglauca(Moench) Voss.) are given.

ISSN:0045-5067    

DOI:10.1139/x78-006

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Allometric relations for tree phytomass distribution on two black spruce (PiceamarianaMill. B.S.P.) sites in interior Alaska were developed and compared with entire unit area samples. Tree component mass equations providedR2values ranging from a low of 0.24 to a high of 0.97, with the majority of values above 0.75. Equations were developed for foliage; live and dead cones; dead branch total, dead branch bark, dead branchwood; live branch total, live branch bark, live branchwood; bole total, bole bark, bole wood; and tree total. Regression equations were developed to predict tree height, distance from crown bottom to ground, crown width, and crown length using basal diameters.R2values for these equations ranged from 0.89 to 0.20. Foliage comprised from 37% to 17% of the total mass for the lowland stand and 50% to 17% of the total tree mass in the upland stand for trees with a diameter class ranging from 0.32 to 7.94 cm. For these same diameter classes, the total bole mass ranged from 11% to 58% and 21% to 61% of the total mass in the lowland and upland stands, respectively. Comparisons of predicted total aboveground tree biomass, measured biomass, and an average-tree-per-diameter-class procedure showed the lowland site predictions were about 6% low and the upland site predictions were approximately 3% high. Using a second, all-tree component method of prediction, results were about 3% low for lowland sites and 4% low for upland sites. A method of prediction using an average stand diameter yielded differences ranging from 31% low for the lowland site to 45% low for the upland site.

ISSN:0045-5067    

DOI:10.1139/x78-007

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Thinning in a white spruce,Piceaglanca(Moench) Voss, forest in interior Alaska stimulated organic matter decomposition in the forest floor as indicated by weight loss of litter and cellulose bags. The general higher weight loss in the most heavily thinned plot is attributed to observed higher average seasonal temperatures. Cellulose bags placed in the boundary between the fermentation–humus and the humus–mineral soil layers of the forest floor showed a significantly higher weight loss than those placed on top of the litter layer. This was attributed to more favorable moisture conditions and a more direct contact with the decomposing microbial populations in the fermentation–humus and humus–mineral soil layers.Regardless of thinning treatment, elements were grouped according to their rate of release from decomposing organic matter as follows: K > Mg > C ≈ P ≈ N ≈ Ca, where potassium is lease resistant. Since relatively small differences in weight loss of litter bags were observed between the treatments, similar studies should extend over a longer period in order to obtain a better understanding of the decomposition proc

ISSN:0045-5067    

DOI:10.1139/x78-008

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Analysis of a 13-stand sample from northern Ontario indicated that the sweetfern blister rust disease (CronartiumcomptoniaeArth.) caused cankers that were associated with significantly reduced height, diameter, and volume growth of jack pine (PinusbanksianaLamb.). Cankered trees were smaller than unaffected jack pine by an average of 20% (range 0–40%) cubic volume and 29% (range 3–53%) board volume.The average size of cankered pines was reduced and directly related to the percentage in the stand that had severe cankers, as these trees seem to have a reduced capacity for competing with other trees. Size difference was negligible in several stands and this was explained as being due to the lack of competition in young stands and to the elimination of many severely cankered trees in older stands. Such trees are prone to domination by other trees and to attack by insects, fire, and wood rots.The merchantable volume of a cankered tree was reduced by about 11% because wood associated with cankers is distorted, resinous, and frequently has enclosed bark.Mortality of seedling-sized pines was not included in the study. Older trees seem to tolerate the presence of cankers, and mortality of these was confined mostly to dominated trees. Cankered pines had a greater tendency to become dominated and die than did unaffected pines, but mortality was considered unimportant because dominated trees add little in terms of stand competition or usable product.

ISSN:0045-5067    

DOI:10.1139/x78-009

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

More decay (higher incidence and greater total length of column) was associated with tapholes in mature sugar maples (AcersaccharumMarsh.) treated with a 250-mg paraformaldehyde pill than with control tapholes. This was apparent 20 months after treatment and at each successive examination to the final measurement at 56 months. Discoloured columns associated with pill-treated tapholes were longer than those associated with control tapholes for the first 8 months. From that time until the final measurement there were no statistically significant differences between lengths of discoloured columns associated with pill-treated and control tapholes. Cambial dieback occurred adjacent to many tapholes but there was no significant difference in closure rates of treated and control tapholes. Results were obtained from dissections and studies of 180 mature trees over a 56-month period in six locations in Vermont in one experiment, and from 75 trees over a 20-month period in three locations each in Vermont, Maine, New York, Pennsylvania, and Michigan in another experiment. The results indicate that repeated use of paraformaldehyde will lead to rapid development of decay in sugar maple trees.

ISSN:0045-5067    

DOI:10.1139/x78-010

出版商:NRC Research Press    

年代:1978

数据来源: NRC